September 18, 2012,
Volume 59, No. 04
Intentionally Unvaccinated Students Put Others at Risk
Parents nervous about the safety of vaccinations for their children may be causing a new problem: the comeback of their grandparents’ childhood diseases, reports a study from the University of Pennsylvania School of Nursing.
Despite the successes of childhood immunizations, wrote Penn Nursing researcher Dr. Alison M. Buttenheim, in the American Journal of Public Health, controversy over their safety has resulted in an increasing number of parents refusing to have their children vaccinated and obtaining legally binding personal belief exemptions against vaccinations for their children.
People who cannot get immunizations because of allergies or compromised immune systems rely on “herd immunity,” the protection they get from a disease when the rest of the population is immunized or immune, explained Dr. Buttenheim. If a high number of children go intentionally unvaccinated because of personal belief exemptions, herd immunity is compromised, she said, giving a disease the chance to spread rapidly.
Dr. Buttenheim and colleagues studied data that more than 7,000 public and private schools report to the California Department of Public Health each year, for some 500,000 kindergarteners. They found that the number of children with one or more personal belief exemptions increased 25 percent in the state from 2008 to 2010. They also found that exempt children tended to aggregate within individual schools, and that a growing number of kindergarteners—both vaccinated and exempt—were attending schools with potentially risky personal belief exemption rates.
“Vaccines are one of the great public health achievements of the last couple of centuries,” Dr. Buttenheim said. “They protect us from diseases that used to routinely kill hundreds of thousands of children in the United States and still kill hundreds of thousands globally. It’s not just important for a child to be vaccinated, it’s important at a population level to have high rates of coverage.”
In 2008, a measles outbreak spread in California. It was traced to a child whose parents had decided not to vaccinate him. He brought the disease back from Europe, infecting other children at his doctor’s office and his classmates. The boy’s parents had signed a personal belief exemption affidavit stating that some or all of the immunizations were against their beliefs, thereby allowing their son to go unvaccinated before entering kindergarten. California is one of 20 states that allow such exemptions.
Nationally, because of generally widespread vaccination coverage among children, vaccine-preventable childhood diseases that once caused substantial disease burdens and death in the United States remain rare occurrences. Measles once infected four million people and killed 4,000 of them each year, mostly young children. With high measles vaccine coverage over several decades, endemic measles was eliminated in the United States as of 2000. The current routine childhood immunization schedule is estimated to prevent 42,000 deaths and 20 million cases of disease and to save $14 billion in direct medical costs per US birth cohort.
Dr. Buttenheim plans to test several interventions at the school level, including new incentive structures for schools to increase adherence rates. She believes the school nurse can play a key role in encouraging parents to get children immunized. “We know everyone is heavily influenced by social norms and pressure,” she explained, and school nurses can set the expectation that children get fully vaccinated. “I think the school nurse can really act as a gatekeeper here, and reset the norm in favor of immunization.”
Researchers Call for Obesity Prevention Efforts to Focus on Community-Wide Systems that Influence Early Life
National data show that currently more than 10 percent of preschoolers in the United States are obese, and an additional 10 percent are overweight. In a published article, a researcher from the Perelman School of Medicine at the University of Pennsylvania, in collaboration with peers and colleagues from across the nation, said that effective strategies to target pregnant women, infants, and toddlers are urgently needed to stop the progression of childhood obesity. The call to action comes just weeks after the release of a recent report from the Institute of Medicine (IOM) and an HBO documentary, The Weight of the Nation, both of which focused on the nation’s growing obesity epidemic. The full text of the article is available in the June issue of Childhood Obesity.
The authors point to evidence which shows that over the past several generations behavioral and societal changes have led to the obesity epidemic, with attendant health and economic consequences demanding new scientific approaches, policy, and actions. Obesity, they say, is a complex problem involving multiple factors including the family, community structures and services, and broad societal forces. That these contributors are interrelated only adds complexity to the issue, which ultimately results in a growing epidemic.
“A systems approach would link interventions in a variety of settings and take into account both behavioral and environmental factors. The importance of taking a broader look at these factors is further evidenced by the recent IOM report which provides a road map for how we can continue to make progress in preventing obesity,” said Dr. Shiriki Kumanyika, professor of epidemiology at Penn Medicine. “In this article, we propose an ambitious but achievable approach that focuses on tackling obesity at the earliest stages of life, and within the larger community, not just at the individual level.”
Evidence increasingly suggests that the risk for childhood obesity begins even before and during pregnancy via maternal obesity and excessive gestational weight gain. Studies show it is likely that obese preschoolers will continue to be obese later in childhood and they may begin to exhibit adverse effects of obesity as early as three years of age.
Additional research shows that progress toward implementing effective and sustainable child obesity prevention strategies requires strengthening current approaches to add a component that addresses pregnancy onward. A review of evidence from basic science, prevention, and systems research supports an approach that begins at the earliest stages of development, and uses a broader community approach to focus on implementing improved healthy behaviors and environmental changes in communities, including food industry and transportation policy.
Penn Researchers Make First All-Optical Nanowire Switch
Computers may be getting faster every year, but those advances in computer speed could be dwarfed if their 1s and 0s were represented by bursts of light, instead of electricity.
Researchers at the University of Pennsylvania have made an important advance in this frontier of photonics, fashioning the first all-optical photonic switch out of cadmium sulfide nanowires. Moreover, they combined these photonic switches into a logic gate, a fundamental component of computer chips that process information.
The research was conducted by associate professor Ritesh Agarwal and graduate student Brian Piccione of the department of materials science and engineering in Penn’s School of Engineering and Applied Science. Postdoctoral fellows Chang-Hee Cho and Lambert van Vugt, also of the materials science department, contributed to the study.
It was published in the journal Nature Nanotechnology.
The research team’s innovation built upon their earlier research, which showed that their cadmium sulfide nanowires exhibited extremely strong light-matter coupling, making them especially efficient at manipulating light. This quality is crucial for the development of nanoscale photonic circuits, as existing mechanisms for controlling the flow of light are bulkier and require more energy than their electronic analogs.
“The biggest challenge for photonic structures on the nanoscale is getting the light in, manipulating it once it’s there and then getting it out,” Dr. Agarwal said. “Our major innovation was how we solved the first problem, in that it allowed us to use the nanowires themselves for an on-chip light source.”
The research team began by precisely cutting a gap into a nanowire. They then pumped enough energy into the first nanowire segment that it began to emit laser light from its end and through the gap. Because the researchers started with a single nanowire, the two segment ends were perfectly matched, allowing the second segment to efficiently absorb and transmit the light down its length.
“Once we have the light in the second segment, we shine another light through the structure and turn off what is being transported through that wire,” Dr. Agarwal said. “That’s what makes it a switch.”
The researchers were able to measure the intensity of the light coming out of the end of the second nanowire and to show that the switch could effectively represent the binary states used in logic devices.
“Putting switches together lets you make logic gates, and assembling logic gates allows you to do computation,” Mr. Piccione said. “We used these optical switches to construct a NAND gate, which is a fundamental building block of modern computer processing.”
A NAND gate, which stands for “not and,” returns a “0” output when all its inputs are “1.” It was constructed by the researchers by combining two nanowire switches into a Y-shaped configuration. NAND gates are important for computation because they are “functionally complete,” which means that, when put in the right sequence, they can do any kind of logical operation and thus form the basis for general-purpose computer processors.
“We see a future where ‘consumer electronics’ become ‘consumer photonics’,” Dr. Agarwal said. “And this study shows that is possible.”